Effects of 1,3-propanediol associated, or not, with butylene glycol and/or glycerol on skin hydration and skin barrier function.

OBJECTIVE: This study aimed to assess the effect of 1,3-propanediol at different concentrations (5%, 10%, or 15%), either applied alone or in combination with butylene glycol (BG) (5%) and/or glycerol (5%), on skin hydration and skin barrier function. The measurements were conducted using capacitance to determine skin hydration and trans epidermal water loss (TEWL) rates to evaluate skin barrier function. METHODS: A total of 30 healthy female subjects participated in the study. Capacitance and TEWL measurements were conducted at multiple time points, including before application and at 15 min, 2 and 8 h after the humectants were applied to the forearms of the subjects. All the subjects provided written informed consent. RESULTS: The 1,3-propanediol in all concentrations and in all combinations (with BG and/or glycerol) increased skin hydration and improved skin barrier function 15 min, 2 and 8 h after application. Glycerol increased the hydration performance of 1,3-propanediol. The application of 1,3-propanediol at a concentration of 15%, either alone or in combination with other humectants, reduced the TEWL to a greater extent than lower concentrations of 1,3-propanediol. Furthermore, the addition of glycerol to 1,3-propanediol 15% improved the skin barrier and reduced TEWL when compared with 1,3-propanediol alone and with the combination of 1,3-propanediol + BG. CONCLUSION: The humectants significantly improved skin hydration and reduced TEWL throughout the 8-h time course. The increase in 1,3-propanediol concentration, as well as its combination with glycerol, provided a greater benefit to the skin, improving both hydration and the skin barrier function.

OBJECTIF: Cette étude visait à évaluer l'effet sur l'hydratation de la peau et la fonction de barrière cutanée du 1,3-propanediol à différentes concentrations (5 %, 10 % ou 15 %), appliqué seul ou en association avec du butylène glycol (5 %) et/ou du glycérol (5 %). Les mesures ont été effectuées à l'aide de la capacitance pour déterminer l'hydratation de la peau et les taux de perte d'eau transépidermique (Trans Epidermal Water Loss, TEWL) pour évaluer la fonction de barrière cutanée. MÉTHODES: Au total, 30 sujets de sexe féminin en bonne santé ont participé à l'étude. Les mesures de la capacitance et de la TEWL ont été effectuées à plusieurs moments, y compris avant l'application, 15 minutes, 2 heures et 8 heures après l'application des produits humectant sur les avant-bras des sujets. Tous les sujets ont fourni un consentement éclairé écrit. RÉSULTATS: Le 1,3-propanediol, à toutes les concentrations et dans toutes les associations (avec le butylène glycol et/ou le glycérol), a augmenté l'hydratation de la peau et amélioré la fonction de barrière cutanée à 15 minutes, 2 heures et 8 heures après l'application. Le glycérol a augmenté les performances d'hydratation du 1,3-propanediol. L'application de 1,3-propanediol à une concentration de 15 %, seul ou en association avec d'autres produits humectant, a réduit la TEWL dans une plus grande mesure que des concentrations inférieures de 1,3-propanediol. En outre, l'ajout de glycérol au 1,3-propanediol 15 % a amélioré la barrière cutanée et réduit la TEWL par rapport au 1,3-propanediol seul et à l'association 1,3-propanediol + butylène glycol. CONCLUSION: Les produits humectant ont significativement amélioré l'hydratation de la peau et réduit la TEWL tout au long des 8 heures. L'augmentation de la concentration de 1,3-propanediol, ainsi que son association avec le glycérol, ont apporté un plus grand bénéfice à la peau, améliorant à la fois l'hydratation et la fonction de barrière cutanée.

Arginine-fructose-glucose from red ginseng extract reduces stiffness of keratin fiber in corneocyte of skin.

PURPOSE: The moisture content of the stratum corneum of the skin changes depending on the external environment. The structure of keratinous fiber protein in corneocyte of the skin changes depending on the amount of moisture. As the moisture decreases, the population of the alpha-helix increases, the beta-sheet deceases, and the stiffness increases accordingly. Here, we investigated the effect of humectants from ginseng on the keratin structure. METHODS: Corneocyte was prepared from dry porcine skin with disc tape and measured through ATR-FT-IR. The signal from amide I of the keratin protein in corneocyte was detected, and the change in the ratio of alpha-helix and beta-sheet was calculated. The test samples were treated on the exfoliated corneocyte, and the degree of change was checked. RESULT: Arginine-fructose-glucose (AFG)-enriched extract of red ginseng was effective in changing the keratin structure and was superior to humectants such as glycerin. However, arginine, mono sugar were not effective, and the AFG form in which two sugars were bound to one amino acid could perform its function. CONCLUSION: The present study suggests that AFG, when applied to cosmetics, is expected to improve skin texture in a different way from existing moisturizers represented by glycerin by reducing the alpha-helix structure of corneocyte keratin.

Differential responses to e-cig generated aerosols from humectants and different forms of nicotine in epithelial cells from nonsmokers and smokers.

In the United States, millions of adults use electronic cigarettes (e-cigs), and a majority of these users are former or current cigarette smokers. It is unclear, whether prior smoking status affects biological responses induced by e-cigs. In this study, differentiated human nasal epithelial cells (hNECs) from nonsmokers and smokers at air-liquid interface were acutely exposed to the e-cig generated aerosols of humectants, propylene glycol (PG), and glycerol (GLY). Mucin levels were examined in the apical washes, and cytokine levels were assessed in the basolateral supernatants 24 h postexposure. The aerosol from the GLY exposure increased mucin 5, subtype AC (MUC5AC) levels in the apical wash of hNECs from nonsmokers, but not smokers. However, the aerosol from GLY induced pro-inflammatory responses in hNECs from smokers. We also exposed hNECs from nonsmokers and smokers to e-cig generated aerosol from PG:GLY with freebase nicotine or nicotine salt. The PG:GLY with freebase nicotine exposure increased MUC5AC and mucin 5, subtype B (MUC5B) levels in hNECs from nonsmokers, but the nicotine salt exposure did not. The PG:GLY with nicotine salt exposure increased pro-inflammatory cytokines in hNECs from smokers, which was not seen with the freebase nicotine exposure. Taken together, these data indicate that the e-cig generated aerosols from the humectants, mostly GLY, and the type of nicotine used cause differential effects in airway epithelial cells from nonsmokers and smokers. As e-cig use is increasing, it is important to understand that the biological effects of e-cig use are likely dependent on prior cigarette smoke exposure.

Optimization of granular formulations of Metarhizium humberi microsclerotia with humectants.

Granular microsclerotial formulations of entomopathogenic fungi deserve attention because of their post-application, in situ production of new conidia that enhance and prolong mycoinsecticidal efficacy against a target pest insect. Because high ambient moisture is a crucial condition to induce fungal development and conidiogenesis on granules, we tested the impacts of the additions of three humectants-glycerin, propylene glycol, and polyethylene glycol 400-on water absorption by pellets incorporating microsclerotia of Metarhizium humberi IP 46 with microcrystalline cellulose or vermiculite carriers, and on the production of infective conidia of IP 46 microsclerotia in ambient humidities suboptimal for routine conidiogenesis. Glycerin facilitated greater and faster absorption of water than the other humectants. Microcrystalline cellulose absorbed low quantities of water without any added humectant whereas vermiculite did not. IP 46 did not grow or sporulate on pellets prepared with or without glycerin at 86% relative humidity (RH) or on control pellets without glycerin at 91% RH; conidial production on pellets prepared with vermiculite or microcrystalline cellulose and 10% glycerin reached 1.1 × 105 conidia/mg and 1 × 105 conidia/mg, respectively, after 20 days of exposure at 91% RH. Hence, these results strongly support glycerin as a suitable humectant for granular microsclerotial formulations of this fungus.

Effects of lowering water activity by various humectants on germination of spores of Bacillus species with different germinants.

The effect of water activity (aw), as lowered by different dietary humectants, on the germination of Bacillus subtilis, Bacillus megaterium and Bacillus cereus spores with germinants that act by different mechanisms has been investigated and compared. Germination of spores of these species by all of the germinants investigated was inhibited as aw decreased, with the general order of efficacy for these non-ionic humectants being sucrose > trehalose > glycerol. The effect of lowering aw on germination by germinant receptor (GR)-dependent germinants was not appreciably altered by varying germinant concentrations, was generally not much more effective with spores lacking coats or an outer membrane, and was less pronounced with heat-activated spores. Analysis of the effect of aw on spore germination via different mechanisms showed that GR-dependent germination was least sensitive to aw, while germination via activation of spore cortex peptidoglycan hydrolysis or dipicolinic acid release was more sensitive. However, germination by high hydrostatic pressure was less sensitive to inhibition by low aw, than was germination by other germinants. Examination of the GR-dependent germination of individual spores indicated that aw acted most strongly in inhibiting the commitment step of germination, while exerting smaller effects on dipicolinic acid release or cortex peptidoglycan hydrolysis.

Understanding the effects of topography on skin moisturization measurement via two-dimensional capacitance imaging.

OBJECTIVE: Methods which assess skin moisturization based on changes in its electrical properties are widely used in both cosmetic and medical research industries. However, the devices themselves often give results which are significantly different to each other. Recently two-dimensional imaging moisturization systems have become commercially available, which have the capability to provide a more detailed assessment of what is contributing to measured skin moisturization. Presented here is a new in vitro method for preparing textured model test substrates for use with these devices, and results of their use to provide a clearer insight into the devices operation. METHODS: A variety of different textured model test substrates were measured using a commercially available skin moisturization measurement device, the Epsilon. The response of the Epsilon was also tested against conventional skin moisturization devices. RESULTS: Surface morphology of model test substrates was found to have a significant influence on the measurement of its electrical properties with both the conventional and two-dimensional skin moisturization measurement devices. Through modification of the areas of the image being assessed for the two-dimensional moisturization mapping device, the parts of the model test substrate in contact with the device were indentified and analysed separately to areas not in contact with the sensor. This provided a more robust assessment of the electrical properties of substrate itself, rather than being influenced by texture like the conventional skin moisturization measurement devices. CONCLUSIONS: While the two-dimensional moisturization mapping systems can be used like a conventional electrical skin measurement device giving a simple overall reading of skin moisturization for the test area, their true value over existing electrical measures comes from its ability to isolate the skin itself from areas which are not in contact with the sensor.

Exposure of Salmonella enterica Serovar Typhimurium to Three Humectants Used in the Food Industry Induces Different Osmoadaptation Systems.

Common salt (NaCl) is frequently used by the food industry to add flavor and to act as a humectant in order to reduce the water content of a food product. The improved health awareness of consumers is leading to a demand for food products with reduced salt content; thus, manufacturers require alternative water activity-reducing agents which elicit the same general effects as NaCl. Two examples include KCl and glycerol. These agents lower the water activity of a food matrix and also contribute to limit the growth of the microbiota, including foodborne pathogens. Little is currently known about how foodborne pathogens respond to these water activity-lowering agents. Here we examined the response of Salmonella enterica serovar Typhimurium 4/74 to NaCl, KCl, and glycerol at three time points, using a constant water activity level, compared with the response of a control inoculum. All conditions induced the upregulation of gluconate metabolic genes after 6 h of exposure. Bacteria exposed to NaCl and KCl demonstrated the upregulation of the osmoprotective transporter mechanisms encoded by the proP, proU, and osmU (STM1491 to STM1494) genes. Glycerol exposure elicited the downregulation of these osmoadaptive mechanisms but stimulated an increase in lipopolysaccharide and membrane protein-associated genes after 1 h. The most extensive changes in gene expression occurred following exposure to KCl. Because many of these genes were of unknown function, further characterization may identify KCl-specific adaptive processes that are not stimulated by NaCl. This study shows that the response of S. Typhimurium to different humectants does not simply reflect reduced water activity and likely involves systems that are linked to specific humectants.

Foundation products have a measureable impact on moisturization.

Multifunctional products are becoming more prevalent in the color cosmetics market. We evaluated four foundation products for in vivo moisturizing benefits using the mini-regression test method. We found that statistically significant long-lasting moisturization was provided by the foundations tested, but only if hygroscopic moisturizing ingredients were present.

Assessment of desiccants and their instructions for use in rapid diagnostic tests.

BACKGROUND: Malaria rapid diagnostic tests (RDTs) are protected from humidity-caused degradation by a desiccant added to the device packaging. The present study assessed malaria RDT products for the availability, type and design of desiccants and their information supplied in the instructions for use (IFU). METHODS: Criteria were based on recommendations of the World Health Organization (WHO), the European Community (CE) and own observations. Silica gel sachets were defined as self-indicating (all beads coated with a humidity indicator that changes colour upon saturation), partial-indicating (part of beads coated) and non-indicating (none of the beads coated). Indicating silica gel sachets were individually assessed for humidity saturation and (in case of partial-indicating silica gels) for the presence of indicating beads. RESULTS: Fifty malaria RDT products from 25 manufacturers were assessed, 14 (28%) products were listed by the "Global Fund Quality Assurance Policy" and 31 (62%) were CE-marked. All but one product contained a desiccant, mostly (47/50, 94%) silica gel. Twenty (40%) RDT products (one with no desiccant and 19 with non-indicating desiccant) did not meet the WHO guidelines recommending indicating desiccant. All RDT products with self- or partial-indicating silica gel (n = 22 and 8 respectively) contained the toxic cobalt dichloride as humidity indicator. Colour change indicating humidity saturation was observed for 8/16 RDT products, at a median incidence of 0.8% (range 0.05%-4.6%) of sachets inspected. In all RDTs with partial-indicating silica gel, sachets with no colour indicating beads were found (median proportion 13.5% (0.6%-17.8%) per product) and additional light was needed to assess the humidity colour. Less than half (14/30, 47%) IFUs of RDT products with indicating desiccants mentioned to check the humidity saturation before using the test. Information on properties, safety hazards and disposal of the desiccant was not included in any of the IFUs. There were no differences between Global Fund-listed and CE marked RDT products compared to those which were not. Similar findings were noted for a panel of 11 HIV RDTs that was assessed with the same checklist as the malaria RDTs. CONCLUSION: RDTs showed shortcomings in desiccant type and information supplied in the IFU.

The cosmetic and dermatological potential of keratin hydrolysate.

BACKGROUND: Although keratin hydrolysates have become established as standard components in hair and nail cosmetics, studies on the moisturizing effects of keratin hydrolysates do not appear among contemporary literature. OBJECTIVES: To test if adding keratin hydrolysate into an ointment base increases hydration of the skin and improves skin barrier function, or diminishes trans-epidermal water loss. METHODS: Formulations were prepared containing 2%, 4%, and 6% keratin hydrolysates (based on weight of the ointment base). The moisturizing properties of keratin hydrolysates were tested by measuring skin hydration, trans-epidermal water loss and skin pH; measurements were carried out at intervals of 1, 2, 3, 4, 24, and 48 h. Testing was conducted on 10 women. RESULTS: As regards hydration, adding 2% keratin hydrolysate to the ointment base is optimal, as an increase of 14%-23% occurs in hydration of the stratum corneum. For trans-epidermal water loss, adding 4% KH to the ointment base is preferential, as this triggers a 26%-46% decrease in trans-epidermal water loss. CONCLUSIONS: Keratin hydrolysate acts as a humectant (it binds water from lower layers of the epidermis to the stratum corneum) as well as an occlusive (it reduces trans-epidermal water loss). The highly favorable properties of keratin hydrolysates are attributed to the wide distribution of keratin hydrolysates molecular weights; low-molecular weight fractions easily penetrate the SC, while high-molecular weight fractions form a protective film on the epidermis. Adding keratin hydrolysates to the ointment base did not cause phase separation even after 6 mo storage.

Changes in thermal resistance of three Salmonella serovars in response to osmotic shock and adaptation at water activities reduced by different humectants.

The purpose of this study was to investigate the effect of osmotic shock and adaptation at low water activity (aw) and the type of humectant used to lower the aw, on heat resistance of three Salmonella enterica serovars (Saintpaul 02-109, Tennessee 2053H, and Elmsbuettel 1236H). The serovars were grown (adapted) or transferred (osmotic shocked) in low-aw broths and subjected to heat treatment at 55°C for up to 45 min; samples were removed at 5-min intervals and immediately placed in an ice-water bath until plating. The aw of tryptic soy broth (TSB) was lowered by the addition of 20% (wt/wt) glycerol (aw 0.94), 4% (wt/wt) sodium chloride (NaCl; aw 0.97), or 35% sucrose (wt/wt) (aw 0.95). The type of humectant and cell adaptation significantly affected the D55°C-value. Cells merely suspended in 20% glycerol broth (i.e., nonadapted) prior to heat treatment showed a larger D55°C-value (3.0 to 3.9 min), when compared with that of cells adapted in the same medium (D55°C-values of 0.86 to 0.98 min). Interestingly, cells adapted to TSB plus glycerol were not more resistant to heat than were the controls. NaCl and sucrose showed a net protective effect for all serovars under both the adapted and nonadapted conditions, with sucrose providing the most protection. Highest D55°C-values were obtained for cultures adapted to TSB plus sucrose. Based on these results, the effect of reduced aw on thermal resistance of Salmonella serovars varies greatly, depending on medium constituents and adaptation of the pathogen in these media.